With all the disastrous news coming out of Iraq, increasing numbers of Americans are starting to believe the United States is doomed to failure and must soon get out. According to the Pew Research Center, 42 percent of Americans now favor bringing U.S. troops home, up from just over 30 percent at the start of the year. Leading elected officials, and not only opponents of the war, are starting to sound the alarm, as has Sen. Lincoln Chafee, that the United States may be headed for a strategic defeat.

On the right, retired Lt. Gen. William Odom argues that the occupation is already a "failure" and that it is time to withdraw the troops. On the left, former Clinton deputy national security adviser James Steinberg and analyst Michael O'Hanlon of the Brookings Institution believe the United States should set a date for departure sometime next year and stay thereafter only if specifically asked by a new Iraqi government. Centrists such as Leslie Gelb, president emeritus of the Council on Foreign Relations, suggest that the United States should acquiesce in a three-way division of Iraq among the Kurds, Sunnis and Shiites.

Some critics, such as retired Gen. Anthony Zinni, argue that insufficient planning, inadequate resources and poor execution have doomed the enterprise. Others feel that the task of turning Iraq into a functioning democracy was always beyond the capacity of the United States.

Reaching the goal of a stable, unified and non-threatening Iraq does look increasingly difficult, but the consequences of abandoning even that minimalist objective could be severe. Leaving Iraq under the pressure of terrorist attacks would be viewed as a strategic defeat of historic proportions for the United States. The message sent around the world would be that enough roadside bombs, suicide attacks and beheadings of civilians can succeed in forcing the United States (and by extension, any government) to abandon its goals. Success in driving out the American superpower would go down in terrorist lore as a great "victory," inspiring new campaigns on new battle fronts all around the world.

Withdrawal under the current circumstances would also entail the very significant risk -- if not probability -- of turning Iraq into a failed state. The departure of U.S. troops would create a security vacuum that would quickly be filled by the most heavily armed and violent groups in Iraq.

Iraqi ethnic, religious and linguistic communities would probably struggle to establish control over that country's vast energy riches. Civil war, ethnic cleansing and genocide on a scale exceeding the breakup of Yugoslavia would be a likely result. Iraq's neighbors -- including Iran, Syria, Saudi Arabia and Turkey -- would probably be drawn in, supplying arms and money to their preferred factions and perhaps even intervening directly. The great irony is that the United States would be left with a new Afghanistan -- a haven for terrorists -- even as it continued to work to stabilize the old one.

While the Bush administration has pledged to stay the course, it has already made several major course corrections, accelerating the return of sovereignty to Iraqis and expanding the role of the United Nations. On June 30 Iraq will cease to be an occupied enemy and become an ally and partner. As Secretary of State Colin Powell has made clear, American troops will then remain at the sufferance of the Iraqis.

If it is to retain that sufferance or, more accurately, if it is to regain it, the United States will need to make adjustments in its military strategy commensurate with the changes it has introduced in its political and diplomatic approaches. Henceforth, American forces cannot afford to destroy villages to save them. They cannot afford to use artillery, gunships and ordnance from fixed-wing aircraft in populated areas, regardless of the provocation. They cannot afford to sacrifice innocent Iraqi civilians to reduce American casualties. They cannot afford to sweep up, incarcerate and hold for months thousands of Iraqis -- many of them innocent -- to apprehend a smaller number of guilty ones. They cannot afford to use pain, privation or humiliation to secure information.

Whether such actions are consistent with the laws of armed conflict is not the relevant criterion. What matters most is that such actions are inconsistent with the treatment of an allied population upon whose sufferance and support this mission depends.

The objective of insurgent tactics is to show that coalition forces cannot protect the civil population while simultaneously provoking responses that will drive up civilian "collateral damage." Our forces cannot entirely escape this dilemma, but they can demonstrate greater sensitivity for Iraqi civilian casualties, first by beginning to keep track of how many innocents are indeed being killed and wounded by insurgent or coalition actions, and then by adjusting tactics and rules of engagement to reduce the figure. American spokesmen in Iraq might talk less about offensive operations to win the war on terrorism and more about protective measures to improve security for the Iraqi public. Emergency and long-term medical attention for civilian victims can be improved and highlighted. Coalition commanders can defer to Iraqi authorities when considering operations likely to produce high collateral damage, and explore the possibilities for local accommodation with tribal, communal and religious elements.

An insurgency cannot be defeated without the support of the population. The United States will not secure that support unless it puts public security at the center of its military strategy. Strong presidential leadership will be required to effect such a fundamental shift in that strategy. In the absence of such a shift, early withdrawal may be the only alternative, with all the consequences that could ensue.

James Dobbins is director of the International Security and Defense Policy Center at the Rand Corp. Philip H. Gordon is a senior fellow in foreign policy studies at the Brookings Institution.